Candela Laser Corporation and Albert Einstein Medical Center will develop and evaluate a pulsed laser system for endodontic therapy based on specific laser target/tissue interaction. Employing laser energy delivered to teeth via a flexible fiber optic, the system will remove diseased pulp and dentin, prepare a root canal and create a hermetic laser-fused apical seal within a tooth. This new laser system will enable endodontists to complete in a single office visit a rapid, definitive, minimally invasive root canal procedure. The research plan is designed to characterize the effects of pulsed dye and holmium yttrium aluminum garnet (Ho1:YAG) laser energy on dental tissue. Freshly extracted human teeth will be irradiated in order to evaluate them for target tissue ablation, the extent of thermal or mechanical damage, and the impermeability of the apical seal. Effectiveness will be measured using light and scanning microscopy, histology, and dye uptake/permeation analysis of specimens. Phase I research is expected to yield information sufficient to lead to extensive additional testing of this system in specimens, and eventually, human subjects. The envisioned procedure has the potential to enhance patient comfort and reduce "chair time" by offering swift, effective, non-objectionable treatment for a widespread disorder. Over 25 million root canal procedures are performed annually, representing a strong pre-existing market, and this versatile laser system holds promise for a host of other applications.